In performing a pipeline-cleaning operation with an aim to reuse an existing pipeline in replacing a refrigerating air-conditioning machine, there is a need to separate and collect residual material such as mineral oil, so as to prevent the residual material mainly including mineral oil having been existing in the existing pipeline, which is collected by means of the pipeline-cleaning operation, from flowing into a newly-constructed refrigerant circuit, by returning to a compressor. This is because refrigerating machine oil such as the mineral oil, having been used for CFC (Chloro Floro Carbon) or HCFC (Hydro Chloro Floro Carbon), containing chlorine, before the replacement, is not compatible with new refrigerant HFC series (Hydro Floro Carbon) not containing the chlorine, after the replacement, or the like, and when a great volume of used refrigerating machine oil remains in a refrigerating cycle in the form of residues, the same results in a foreign material (contamination), and there is a possibility that problems such as damaging of the compressor occurs.
Consequently, hitherto, a technology for separating and collecting the foreign material (mainly used refrigerating machine oil) collected in the pipeline-cleaning operation is developed, and as an example, there is a technology in which an accumulator is used as a separating device for separating a refrigerant and the foreign material, and the separated and collected foreign material is collected in a collecting container provided below the accumulator (for example, refer to the patent document 1). Further, as a technology for collecting separated and collected foreign material into a collecting container using an accumulator as a separating device for a refrigerant and the foreign material, there is a technology in which a pipeline for degassing a collecting container is connected to an outlet pipe of an accumulator to increase an oil collecting speed, so that an increase of a suction effect by an extent of a pressure loss difference of the pipeline is utilized (for example, refer to the patent documents, 2, 3, and 4).
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2003-302127 (FIG. 1, and FIG. 2), Patent Document 2: Japanese Unexamined Patent Application Publication No. 2004-069101 (FIG. 1, and FIG. 3), Patent Document 3: Japanese Unexamined Patent Application Publication No. 2004-085037 (FIG. 1, and FIG. 2), and Patent Document 4: Japanese Unexamined Patent Application Publication No. 2004-219016 (FIG. 1, and FIG. 2)